Those sparkplug wire resistances sound high to me. I just went out in the garage and measured a couple new spiral wound sparkplug wires.  They averaged about 3760 ohms per foot. If I can remember correctly, even the old carbon wires were not as high of a resistance as you reported, maybe others will chime in. When you get the new sparkplug wires it will be interesting to see what they measure.  Rotor and sparkplug gap is what the voltage must overcome. I don't know off hand what the size hole is in a Ford rotor but if you can find something that size to slip the rotor onto, a dial indicator can be used to compare the tip to that of a known good rotor.  I recently found the rotor in my distributor to be eroded by .010"  but that's another story for a new thread. 

64F100 57FAIRLANE500

Thank you for your detailed responses! I understood that increased resistance would demand more voltage on the secondary side, but the nuances of the current/voltage/magnetic fields/oscillation on the primary side are pretty nebulous to me so I wasn’t sure whether the primary side would also see increased current or voltage in some way. I have found that some of my plug wires are over 32k ohms, and even the coil to cap wire is over 12k. Those resistances, along with the “E” type rotor on the distributor, must be working the ignition system harder than intended.

Before I install the pertronix I’m going to see if there is any evident change in spark quality from just changing the plug wires, just out of curiousity.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Voltage rating is only part of the story when it comes to capacitors. Ignition Service is rough duty. It isn't that they are a high-tech product, after all they've been around for 100 years now, but apparently modern manufacturers can't build them to a low price point any longer. Not in the small, compact package used when mounted internally inside a distributor anyway. The other criterion other than voltage rating is known as Dv or rise time. Kind of related to current, I expect.

So what you have to look at when actually choosing a capacitor for points & condenser applications is whether it can meet the ignition specs. There are very compact yet high voltage capacitors available made by metal vapor deposition, these are tempting to use because they will so easily fit inside distributors, but they simply won't hold up. Suitable capacitors tend to be a little on the chunky side, physically speaking. There's nothing that says it must be mounted inside the distributor, btw.

As secondary resistance increases, the voltage necessary to overcome it must also increase. That in itself will add stress to the secondary and primary circuits. I've never really thought of the added stress as detrimental to the points or condenser. An open sparkplug wire, however, will drive up the induced voltage to it's max and that has been known to cause coil damage.  It appears most all the points/condenser issues, IMHO, are related to poor quality condensers.  Use a 1KV rated capacitor as stated by Lord Gaga.  If I remember correctly, there's quite a surge at the moment the points open as seen on an oscilloscope. It's the condenser that takes this surge by momentarily taking the + end of the secondary winding in the  coil to ground to provide a rapid collapse of the field. I've gotten more than one good jolt from rapidly simulating the points with a wire in my bare fingers.  That surge on the condenser when the points open can be up to 200V or more.  I often wonder if the present condensers now on the market are only good for about 12V? or somewhere close to that.   Besides mechanical wear, 2 things cause points to go bad, 1) excessive arcing caused by a marginal condenser and 2) excessive current possibly from not enough resistance in the primary circuit - the resistor itself, or a coil not matched for points/condenser.  Hard question to answer, hope this makes some sense. 

64F100 57FAIRLANE500

Does anyone know whether excessive resistance in the spark plug wires could contribute to breakdown at the points or condenser?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Robs36ford, the car has a Delco 12SI alternator (78A) and voltage has been observed in the 13.5-14.6 range.

Saltshaker, I have seen the same specs posted for the EBC1487 but I don’t know why because they are totally wrong. The coil has an internal resistor and actual primary resistance is 3.0 ohms. You are correct that the “extra” 1.5 ohms of resistance cannot be bypassed, but I have found using the 12v supply during cranking from the starter solenoid still helps.

I found this article elsewhere regarding condenser failure: http://www.nonlintec.com/sprite/cap_failure/
I think Lord Gaga has the right idea about sourcing a modern capacitor that is up to the task as opposed to the mixed-bag indifferent-quality parts that are readily available. All that being said, since distributor access is so unpleasant on my ‘54 (especially in a roadside emergency situation) I have ordered Pertronix 1281 and will carry my best set of points and a condenser as “just in case” parts.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

peeeot,
This is my first time posting on the forum. Hope this might help.
Your problem may be with the ballast resistor.  Did you have one on the coils that failed?
Depending on the coil you are using, the ballast resistor (if you had one) needs to be compatible with the coil.
The original 56 Ford coil primary winding should be around 1.5 ohms at room temperature.  The ballast resistor for the 56 should be about 1.5 ohms, giving a total primary circuit resistance of 3 ohms. 
So what happens if they aren’t?  You will eventually burn up your coil and possibly your points without one because at low RPM the dwell time, increases causing more current to travel through the primary coil and points.  The fix is to install a ballast resistor, in this case a 1.5 ohm version for a total of 3 ohms.  This is what the system was designed to use.
If you don’t have a ballast resistor you might want to get one, and also make sure you’re coil primary winding is 1.5 ohms plus or minus a quarter ohm.
Another solution is to use one of “Internal Ballast” coils. They don’t really have an internal ballast they just have a somewhat lower ohm primary winding and you can get by without a ballast resistor. 
I know some people insist that they do have a ballast, but if that was true how do you hook up a bypass cold starting circuit?  There is no third terminal.  Also, there is the heat problem.  An internal ballast would heat up the coil which is already on the edge of being a barbecue grill.  Better to have the heat on the outside.
Some British coils did have three terminals with internal ballasts, but the Lucas Company who forever ruined the British automotive electrical industry's reputation made them, and anything they built was sketchy to start with.
Don
I checked the Carquest EBC1487 coil and it's primary resistance is .3 to 1.0 ohms.

just go with the dura spark,easey to inst and works. I was hard to convince, but gave in and should have listened would have saved some gray hair

What is the min and max voltage of the voltage regulator ?
Too high will burn point and fail Condesor.


1936 Ford 3W Coupe : 56 T-Bird 312, 47 Packard 3 speed, 40 juice brakes.
1968 Merc Cyclone FB GT 390, Getting a better front clip!
1977 Ford F-250 Supercab RWD Explorer Long box.
1976 Chev Camaro RS LT
Future rebuild : 1949 Ford F-1

Sorry to hear of your troubles. After 2 Chinese condenser failures I installed a Pertronix II. I used their coil and kept the ballast resistor. I have never ever used a coil with an internal resistor and converted many 6 volt cars to 12 volts. Pertronix told me on the phone either way with the ballast resistor use, there was only less high voltage going to the plugs. I choose to have the lower voltage because I figured the coil would be cooler and engine is only 8.1 stock anyway. I have never had any failure or even an engine miss. I’ve cleaned the inside of the cap once in 10 years and that’s it.. good luck. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.